Switchable Pi shape antenna

ABSTRACT

A mobile device including a housing having a distal end, and electronics disposed in the housing configured to operate the mobile device. A connector is coupled to the electronics, and a Pi-shaped antenna has a coupling coupled to the connector to create a resonance using the connector. The Pi-shaped antenna and the connector are configured to wirelessly send and receive the wireless signals. An impedance matching network matches the impedance of the electronics to the Pi-shaped antenna. In some embodiments, the impedance matching network is switchable by the electronics and is configured to match an impedance of the electronics to the Pi-shaped antenna in at least two states, over multiple RF bands.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/274,474, filed May 9, 2014 by Hongwei Liu, et al. andentitled “SWITCHABLE PI SHAPE ANTENNA,” which is incorporated herein byreference as if reproduced in their entirety.

FIELD OF DISCLOSURE

This disclosure is directed to antennas, and more particularly to lowprofile antennas used in advanced mobile devices including smartphonesto cover popular bands.

BACKGROUND

Wireless mobile devices including smartphones require low profileantennas to meet desired product form factors. The available innerdimension (ID) of these devices is limited due to numerous factors,including other component layout design.

The conventional T-shape antenna is commonly used in smartphones, whichT-shaped antenna is good to cover third generation (3G) bands without aUSB connector presented in the device housing. In fourth generation (4G)long term evolution (LTE) devices, the more popular bands are 704-960MHz (LTE B17, B20, G850, G900) & 1710-2170 MHz (DCS, PCS, AWS) to2500-2690 MHz (LTE B7). The conventional T-shaped antenna is limited inband coverage and is not ideally suitable for these popular bands.

SUMMARY

A mobile device operable over a plurality of bands using an antenna, aconnector configured to create a resonance, and having a passive orswitchable impedance matching network.

In one embodiment, the mobile device comprises a housing having a distalend, and electronics disposed in the housing and configured to operatethe mobile device. The electronics are configured to communicatewireless signals including voice calls and text messages. A connector iscoupled to the electronics. A Pi-shaped antenna is disposed at thehousing distal end, the Pi-shaped antenna having a coupling coupled tothe connector and configured to create a resonance using the connector.The Pi-shaped antenna and the connector are configured to wirelesslysend and receive the wireless signals. An impedance matching network iscoupled between the electronics and the Pi-shaped antenna, the impedancematching network configured to match an impedance of the electronics tothe Pi-shaped antenna.

In some embodiments, the impedance matching network is switchable by theelectronics and configured to match an impedance of the electronics inat least two states, over multiple RF bands. In some embodiments, thePi-shaped connector has a first leg comprising the coupling, a secondleg and third leg, the first leg coupled to the connector, the secondleg and the third leg forming a second stripline and a third stripline,respectively. The Pi-shaped antenna is a stripline antenna, and theimpedance matching network comprises a switch, capacitors and inductors.the Pi-shaped antenna is disposed along an edge of the housing distalend.

In some embodiments, the connector is one of a USB connector, anearphone connector, a microphone connector and a memory slot connector.The electronics may comprise an RF driver configured to operate in longterm evolution (LTE) band B17, B20 and B7, wherein the antenna and theconnector create the resonance at band B7. The connector has a shell,wherein the coupling is coupled to the shell.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, wherein likenumbers designate like objects, and in which:

FIG. 1 illustrates a mobile device having a switchable Pi-shapedantenna, a connector, and an impedance matching network;

FIG. 2 illustrates the impedance matching network configured as apassive network;

FIG. 3 illustrates a perspective view of one embodiment of the antennalayed out over a backplane at one end of a printed circuit board (PCB);

FIG. 4 illustrates a mobile device including an antenna and a USBconnector at the center of the device;

FIG. 5 illustrates a typical return loss for the antenna for band B20and B7;

FIG. 6 illustrates the impedance matching network configured as aswitchable network to selectively tune the driving circuit to theantenna for different bands;

FIG. 7 illustrates a return loss for two different states;

FIG. 8 illustrates radiation efficiency for two different states; and

FIG. 9 illustrates another embodiment of a mobile device.

DETAILED DESCRIPTION

This disclosure provides a mobile device including a low profilePi-shaped antenna including a switchable design configured to covermultiple popular 4G LTE bands from B17 to B7, as well as a high bandB41. A Pi-shaped antenna is defined as antenna having at least two armseach coupled to a radiating member and together forming the shape of thegreek symbol Pi.

Referring to FIG. 1, there is shown a mobile device 10 including aswitchable Pi-shaped antenna 12 having three arms, IL1, IL2 and couplingS1. Coupling S1 in combination with another component, such as aconnector as will be described hereafter, is advantageously configuredto provide a resonance to create a high band of the Pi-shaped antenna12, thus extending the bandwidth of the antenna on the mobile device 10.In addition, an impedance matching network 14 is configured to impedancematch the antenna 12 to a radio frequency (RF) drive circuit 16 formingpart of the device electronics 18. Impedance matching network 14 may bepassive or active as will be described below. Drive circuit 16 iscoupled to impedance matching network 14 via a feedpoint 19, andincludes a RF transceiver operable to communicate over multiple RFbands, such as LTE bands B17, B20 and B7. Bands LTE B17, B20, G850, G900are 704-960 MHz) & band LTE B7 is 1710-2170 MHz (DCS, PCS, AWS) to2500-2690 MHz.

Electronics 18 form part of a printed circuit board (PCB) 20 and areconfigured to operate the mobile device in the above mentioned bands.Electronics 18 may include a processor, memory, input/output circuits, adisplay, wireless transceivers and a battery, as are conventional inmobile devices, including smartphones, tablets and so forth. Forinstance, the electronics 18 of mobile device 10 is operable to placeand receive voice calls, text message, images, video files, game files,and other wireless communication signals, such as a mobile phone. A PCBground is shown at 22, and may form an RF ground and backplane forantenna 12. Coupling S1 couples the drive circuit 16 of electronics 18to feedline 26 of antenna 12. Coupling S1 also is coupled to a deviceconnector 30, with coupling S1 comprising a capacitive coupling. Theimpedance matching network 14 is controlled by electronics circuit 18and enables the antenna 12 to be selectively switched between two statesto effectively cover multiple bands, including the popular 4G LTE bandsfrom low bands B17, B20 to high bands B7, and B41 if desired.

FIG. 2 illustrates a schematic of the impedance matching network 14forming a passive impedance matching network. The impedance matchingnetwork 14 comprises inductor L1, capacitor C1, C/L components, andinductor L2, where inductor L2 is used for matching the impedance of theantenna 12 for both the low and the high bands. By way of example,impedance matching network 14 is configured to impedance match thedriver circuit 16 to antenna 12 over the frequency range from low bandsband B17 and B20 to high band B7 and B41. In one embodiment the antenna12 is a stripline antenna and is also tuned by the coupling S1, and thedimensions of the components of impedance matching network 14,specifically the length of inductors L1 and L2, and the IL2/coupling ofcoupling S1.

Referring to FIG. 1, by way of example in one embodiment, dimension D is8 mm, the length of IL1 is 22 mm, and the length of IL2 is 30 mm,depending on the PCB dimensions. Inductor L1 may have a value of 2 nH,and capacitor C1 may have a value of 1.5 pF, and L2 may have a value of4.7 nH. The feedpoint 19 is off the center of the PCB 10 mm. Antennaarms IL1 and IL2 are straight and thick to improve the low band.Coupling S1 couples the drive circuitry 16 of the PCB 20 to the antennaradiators with USB to create the high band. In other embodiments, thevalues and dimensions of these components may be different andlimitation to these values and dimensions is not to be inferred.

FIG. 3 illustrates a perspective view of one embodiment of device 10including the antenna 12 with the passive matching network 14 layed outover a backplane 22 at one end of the printed circuit board (PCB) 20.The PCB 20 includes electronics 18 of the device 10, driving a firstfeedline 26 and a second switchable feedline 28 comprising the Pi-shapedantenna 12.

FIG. 4 illustrates device 10 having the Pi-shaped antenna 12 formed atthe distal end of the device 10, and proximate connector 30 which iscoupled to electronics 18. For instance, the connector 30 may comprise aUSB connector positioned in the center of the device, as shown.Advantageously, the coupling S1 forming the first arm of the antenna 12is coupled to the shell of the connector 30 and the ground 22 to createanother resonance covering the high band B7, thus expanding thebandwidth of the antenna 12. The coupling S1 can also be coupled toother device connectors 30, such as a speaker/earphone connector, amicrophone connector, a memory slot connector, a receiver, a metal coverof the device, or any other components, or any other kinds of ground onthe PCB board (at center or in corner) to create one more high bandresonance, such as at 2.6 GHz to cover band B7. This is a new way to usethe environment to improve antenna bandwidth for a portable mobilecommunication device. The distance between coupling S1 and theconnector/components/ground on PCB board, the shape of coupling S1, thematerial between them, all effect antenna performance. For differentphones/different environments, the shape of antenna 12, the deviceconnectors and the location thereof may vary, and the S1 coupling incombination therewith creates the high band resonance.

FIG. 5 illustrates a typical return loss for the antenna 12 having thepassive impedance matching network 14 from band B20 to band B7.

FIG. 6 illustrates impedance matching network configured as a switchableimpedance matching network. Impedance matching network 14 is configuredto have two (2) states to more effectively tune the antenna 12 for twobands, such as a low band in a first state, such as B17 and B20, and ahigh band in a second state, such as B7. The impedance matching network14 includes a switch SW1 controlled by driver 18 and configured toselectively configure the various components L1, L2, C1 and C2 in thefirst state and the second state. The switch SW1 may be a single pullfour throw (SP4T), although other types of switches may be used and arewithin the scope of this disclosure.

FIG. 7 illustrates a return loss for the antenna 12 in the two differentstates, for state 1 and state 2. State 1 provides a reduced return lossfor band B17 as compared to state 2, whereas state 2 provides a reducedreturn loss for bands B5 and B8 as compared to state 1. The electronics18 selectively establishes the 2 states of operating the antenna 12, andmore than 2 states are possible and within the scope of the presentdisclosure.

FIG. 8 illustrates the radiation efficiency of the antenna 12 in state 1and state 2 for two bands, band B17 and band B7.

FIG. 9 illustrates a second embodiment of a device 40 with the Pi-shapedantenna 12 removed and placed on the back of the device 40 forillustration. The switchable impedance matching network 14 is shown inthe left corner of device 40, and the USB connector is shown in theright corner.

The impedance matching network 14 can also include active components ifdesired. For instance, active components can provide gain control and/orbeam steering may be established.

Advantageously, the capacitively coupled Pi-shaped antenna with aswitchable impedance matching network enables advanced mobile devices,such as those providing 4G, 5G and other versions, to provide coveragein desired bands using a low profile antenna.

While this disclosure has described certain embodiments and generallyassociated methods, alterations and permutations of these embodimentsand methods will be apparent to those skilled in the art. Accordingly,the above description of example embodiments does not define orconstrain this disclosure. Other changes, substitutions, and alterationsare also possible without departing from the spirit and scope of thisdisclosure, as defined by the following claims.

The invention claimed is:
 1. A wireless communication device,comprising: electronics disposed on a printed circuit board (PCB) andoperable to communicate over multiple radio frequency (RF) bands; and aPi-shaped antenna consisting of a radiating stripline, a first arm and asecond arm formed in a shape of greek symbol Pi, the first arm and thesecond arm separately corresponding to two legs of the shape of thegreek symbol Pi, the first arm including a coupling component of thePi-shaped antenna, wherein the coupling component is coupled to aconnector of the wireless communication device to provide a firstresonance over a first band of the multiple RF bands, and wherein thesecond arm is coupled to the electronics via an impedance matchingnetwork to provide one or more second resonances over the multiple RFbands.
 2. The wireless communication of claim 1, wherein the couplingcomponent is coupled to the connector via capacitive coupling.
 3. Thewireless communication device of claim 1, wherein the connector has ashell, wherein the coupling component is coupled to the shell.
 4. Thewireless communication device of claim 1, wherein the impedance matchingnetwork is switchable and configured to match an impedance of theelectronics to the Pi-shaped antenna in at least two states havingdifferent frequency ranges.
 5. The wireless communication device ofclaim 4, wherein in a first state of the at least two states, theimpedance matching network is operated to provide a resonance over afirst frequency range covering the first band, and wherein in a secondstate of the at least two states the impedance matching network isoperated to provide a resonance over a second frequency range notcovering the first band.
 6. The wireless communication device of claim4, wherein the electronics are configured to selectively establish theat least two states.
 7. The wireless communication device of claim 6,wherein the impedance matching network comprises a switch to enableselection of the at least two states.
 8. The wireless communicationdevice of claim 1, wherein the Pi-shaped antenna is disposed along anedge of a housing of the wireless communication device.
 9. The wirelesscommunication device of claim 1, wherein the multiple RF bands comprisethe first band and a second band lower than the first band.
 10. Thewireless communication device of claim 9, wherein the first bandcomprises a Long Term Evolution (LTE) band B7 or LTE band B41.
 11. Thewireless communication device of claim 1, wherein the second arm iscoupled through an impedance matching network to the electronics via afeedpoint to provide the one or more second resonances over the multipleRF bands.
 12. The wireless communication device of claim 1, wherein theimpedance matching network is controllably operated in at least twostates having different frequency ranges.
 13. The wireless communicationdevice of claim 12, wherein the impedance matching network comprises aswitch controlled to selectively switch between the at least two states.14. The wireless communication device of claim 12, wherein theelectronics comprises a drive circuit coupled to the impedance matchingnetwork to selectively switch between the at least two states.
 15. Thewireless communication device of claim 1, wherein the impedance matchingnetwork is on a backplane.
 16. The wireless communication device ofclaim 1, wherein the first resonance is based on a dimension of thecoupling component.
 17. The wireless communication device of claim 1,wherein the first resonance is based on a shape of the couplingcomponent.
 18. The wireless communication device of claim 2, wherein thefirst resonance is based on material disposed between the couplingcomponent and the connector in the device.
 19. The wirelesscommunication device of claim 1, wherein the connector is a speakerconnector, a earphone connector, a microphone connector, a memory slotconnector, a USB connector, a receiver or a metal cover of the device.20. The wireless communication device of claim 1, wherein the couplingcomponent is capacitively coupled to a ground of the PCB.
 21. A wirelesscommunication device, comprising: electronics disposed on a printedcircuit board (PCB) and operable to communicate over multiple radiofrequency (RF) bands; and a Pi-shaped antenna consisting of a radiatingstripline, a first arm and a second arm formed in a shape of greeksymbol Pi, the first arm and the second arm separately corresponding totwo legs of the shape of the greek symbol Pi, the first arm including acoupling component of the Pi-shaped antenna, wherein the couplingcomponent is capacitively coupled to a ground of the PCB to provide afirst resonance over a first band of the multiple RF bands, and whereinthe second arm is coupled to the electronics via an impedance matchingnetwork to provide one or more second resonances over the multiple RFbands.
 22. The wireless communication device of claim 21, wherein thecoupling component is coupled to a connector of the communicationdevice.
 23. The wireless communication device of claim 22, wherein theconnector is a speaker connector, a earphone connector, a microphoneconnector, a memory slot connector, a USB connector, a receiver or ametal cover of the device.
 24. The wireless communication device ofclaim 22, wherein the coupling component is capacitively coupled to theconnector and wherein the first resonance is based on material disposedbetween the coupling component and the connector in the device.
 25. Thewireless communication device of claim 22, wherein the couplingcomponent is capacitively coupled to the connector and wherein the firstresonance is based on a dimension of the coupling component.
 26. Thewireless communication device of claim 22, wherein the couplingcomponent is capacitively coupled to the connector and wherein the firstresonance is based on a shape of the coupling component.
 27. Thewireless communication device of claim 21, wherein the multiple RF bandscomprise the first band and a second band lower than the first band. 28.The wireless communication device of claim 21, wherein the first bandcomprises a Long Term Evolution (LTE) band B7 or LTE band B41.
 29. Thewireless communication device of claim 21, wherein the impedancematching network is switchable and configured to match an impedance ofthe electronics to the Pi-shaped antenna in at least two states havingdifferent frequency ranges.